At least seven people were killed Sunday, including the suspected gunman, when a man fired on worshipers at the Sikh Temple of Wisconsin in Oak Creek, police said.

Two police officers exchanged fire with the suspected gunman and one of them was seriously wounded, said Bradley Wentlandt, chief of the nearby Greenfield Police Department.

"The two Oak Creek officers who responded are clearly heroes in this situation today," Wentlandt said in a telephone interview.

The first officer who responded exchanged fire with the gunman and was shot several times, Wentlandt said. "A second officer on the scene immediately engaged the suspect and shot and killed him," he said.

A Milwaukee hospital is treating the wounded officer and two other victims. All are in critical condition at Froederdt Hospital. Chief Medical Officer Lee Biblo said the three victims are all adult men.

Hospital spokeswoman Carolyn Bellin said one of the victims had gunshot wounds to the face and extremities, and another had wounds to his abdomen.

Wentlandt said police do not believe there was a second gunman. Officers completed a sweep of the temple area in the Milwaukee suburb and do not believe there are other victims, he said.

Wendlandt, who was designated by Oak Creek police as their spokesman, said the police officer who was shot was in surgery and doctors "think he's going to recover," he said.

Among those shot was Satwant Kaleka, president of the temple, Wentlandt said. Phone calls to his home went unanswered.

Police found four of the dead inside the temple and three, including the gunman, outside. It was not clear how many others were wounded.

Police received several 911 calls about the shooting at 10:25 a.m. CT, and the first officer on the scene engaged a shooter outside the temple, said Wentlandt.

Ven Boba Ri, one of the temple members, told the Milwaukee Journal Sentinel that the shooter was a white male in his 30s. Ri said the gunman was "not an insider" and called the attack "pretty much a hate crime.''

Police have not indicated any known motive yet.

Ri told the newspaper that the shooter walked up and shot a priest who was standing outside, then went inside the temple and began firing.

"Our hearts go out to the victims and their families as we all struggle to comprehend the evil that begets this terrible violence," Wisconsin Gov. Scott Walker said.

President Obama said in a statement that he was "deeply saddened" by the shooting and offered whatever federal support is needed for the investigation.

"At this difficult time, the people of Oak Creek must know that the American people have them in our thoughts and prayers, and our hearts go out to the families and friends of those who were killed and wounded," Obama said. "As we mourn this loss which took place at a house of worship, we are reminded how much our country has been enriched by Sikhs, who are a part of our broader American family."

Sunny Singh, 21, of Milwaukee, said a friend pulled into the temple's parking lot, heard shots and saw two people fall down. The friend then saw the shooter reload his weapons and head to the temple's entrance, Singh said.

In Washington, the Indian Embassy was monitoring the situation and was in touch with the National Security Council over the incident, CNN reported.

Sikhs are a tiny minority among religious groups in the USA. A survey of Asian-American religions by the Pew Forum on Religion & Public Life, released in July, found Sikhs are 1% of the nation's 18.2 million Asian Americans.

Sikhism is a religion founded in the 15th century by Guru Nanak Dev in the Punjab region of what is now Pakistan. It is among the largest organized religions in the world, with more than 20 million Sikhs worldwide, most in India.

Sikh rights groups have reported a rise in bias attacks since the Sept. 11, 2001, terrorist attacks. The Washington-based Sikh Coalition has reported more than 700 incidents in the U.S. since 9/11, which advocates blame on anti-Islamic sentiment. Sikhs don't practice the same religion as Muslims, but their long beards and turbans often cause them to be mistaken for Muslims, advocates say.

Observant Sikhs do not cut their hair; male followers often cover their heads with turbans - which are considered sacred - and refrain from shaving their beards. It is a tenet of their faith that uncut hair represents the perfection of God's creation.

But the turban also attracts violence to individuals and their places of worship. In the wake of the Sept. 11, 2001, terror attacks, four drunk teenagers set fire to the Gobind Sadan, a Sikh house of worship in Hastings, N.Y.